Study Links Infuse Bone Graft it to Male Infertility

Medtronic’s Infuse bone graft product has been linked to a higher risk of infertility in men when used in a certain type of surgery. The finding is surprising, as earlier research had purportedly not seen such side effects with Infuse. Less surprising – the earlier, more favorable Infuse research was paid for by Medtronic Inc.

Infuse Bone Graft contains recombinant human Bone Morphogenetic Protein (rhBMP-2), a protein released naturally by the body. It is approved to treat a spinal condition called Degenerative Disc Disease, as well as open fractures of the tibia. It is also approved for use in two dental bone grafting procedures: sinus augmentation and localized alveolar ridge augmentation.
As we’ve reportedly previously, the Infuse product has had a controversial history. In July 2008, the Food & Drug Administration (FDA) warned that the use of Infuse Bone Graft and similar products had caused serious problems when they were used off-label in cervical spine (neck) surgeries. Patients reported difficulty swallowing, breathing and speaking. Several required emergency treatment, including tracheotomies and the insertion of feeding tubes, as well as second surgeries.

In 2009, a surgeon at the U.S. Army’s Walter Reed Hospital was accused of falsifying data for Medtronic-paid Infuse study involving wounded soldiers. That same year, questions were raised concerning another Infuse study at Walter Reed, and whether soldiers involved in it had given informed consent before spine surgery.

This new Infuse study was published online in the June issue of The Spine Journal. According to Bloomberg News, the study found that a little over 7 percent (5 out of 69) of male patients who underwent anterior lumbar fusion with Infuse developed retrograde ejaculation – a condition in which semen is misdirected into the bladder. Of those who did not receive the product, just .06 (1 out of 174) suffered the complication.

Retrograde ejaculation can cause either permanent or temporary sterility in men. The new study estimates 1,000 men may be faced with sterility each year from using Infuse.

According to The New York Times, the male sterility issue did turn up in a Medtronic-paid study that was published in 2002, right after Infuse was approved. But the researchers conducting the trial attributed the complication to issues with surgical technique. And they actually divided patients with the complication by surgical technique, not by whether or not they received Infuse.

Now Dr. Eugene J. Carragee, the Stanford University surgeon who conducted The Spine Journal study, has questioned the decision of the first researchers to divide patients with retrograde ejaculation by surgical technique, the Times reports. Dividing the men into groups via who received Infuse and who did not would have been the standard way to present clinical trial results, he said.

Incidentally, the researchers who conducted the earlier Infuse study – Dr. J. Kenneth Burkus and Dr. Thomas A. Zdeblick – have each received millions of dollars from Medtronic in consulting fees or royalty payments, according to the Times. Those doctors have defended themselves by asserting that not enough men in their study suffered from the retrograde ejaculation to link the side effect with Infuse.

A spokesperson for Medtronic told Bloomberg News that the company reported the retrograde ejaculation complication to the FDA when it sought approval for Infuse. The spokesperson also said Medtronic broke down the trial results depending on whether patients received Infuse or not. Retrograde ejaculation is also noted on the Infuse label as a possible complication.

An editorial published in The Spine Journal notes that since its approval, doctors have reported several complications associated with Infuse. In addition to potentially life-threatening airway complications seen when it is used in neck surgery, other Infuse side effects have included inflammatory reactions, sterile cyst formation, bone damage, and loss of alignment. The editorial also points out that there is no firm evidence Infuse improves outcomes for patients.

According to The New York Times, the author of that editorial, Dr. James D. Kang of the University of Pittsburgh, also surmised that the differing conclusions regarding retrograde ejaculation between the earlier Infuse study and the most recent research could have been the result of Medtronic’s financial support for the first trial.

â€œThere does not seem to be any rational explanation for these observational differences,â€ Dr. Kang wrote.